Hormone replacement therapy (HRT) has been used successfully to treat a variety of conditions, such as osteoporosis, increased risk of cardiovascular disease in post-menopausal women and climacteric symptoms, such as hot flashes, decreased libido and depression. However, HRT with estradiol (E2), either alone or in combination with progestin, can lead to undesirable effects. In fact, a recent Women's Health Initiative (WHI) study was abruptly halted when preliminary results showed that HRT was associated with a 35% increased risk of breast cancer.
Breast cancer can be treated or prevented by using a so-called selective estrogen receptor modulator (SERM), such as tamoxifen. (Before the approval of tamoxifen, breast cancer treatment of pre-menopausal women often included removing the ovaries in order to reduce the cancer-stimulating effect of estrogen.) Tamoxifen appears to selectively block the cancer-inducing effects of estrogen in breast tissues of pre-menopausal women. Another SERM, raloxifene, has been approved for treatment of osteoporosis as an alternative to estrogen replacement. In addition to selectively inducing estrogenic effects in bone tissue, long-term administration of raloxifene was also shown to be associated with reduction in the rate of breast cancer in the Multiple Outcomes of Raloxifene Evaluation (MORE) study.
While SERMs such as tamoxifen and raloxifene provide selective reduction in estrogen's cancer-inducing effects in the breast, they are not without their risks. For example both tamoxifen and raloxifene therapy have been associated with increased incidence of hot flushes, and tamoxifen therapy has been shown to increase the risk of uterine (endometrial) cancer.
Despite the success of estrogen replacement therapy in treating osteoporosis, coronary heart disease and climacteric symptoms, and of SERMs like tamoxifen and raloxifene in treating breast cancer and osteoporosis, there remains a need for compositions having estrogenic properties. Additionally, given the increasing cost of producing drug compounds, there is a need for additional estrogenic compositions that may be obtained from natural sources.
Various cultivars of Rheum palmatum L of the Polygonaceae family are grown in China in Qinghai, Gansu and Tibet provinces. Various other varieties grow all over the world. The root is collected in the late autumn when the plant is withering or in the spring before sprouting. It is washed clean, rootlets are removed, decorticated, cut and dried.